Researchers are suggesting that exposure to interstellar clouds may have triggered multiple ice ages on Earth, changed the chemistry of the atmosphere on the planet and eventually led to the emergence of humankind.
“Stars move, and now this paper is showing not only that they move, but they encounter drastic changes," he added.
The shield is filled with charged particles which are emitted from the sun and are known as the solar wind.
When Earth was without the protection of the heliosphere, it was then exposed to the interstellar medium.
"This cloud was indeed in our past, and if we crossed something that massive, we were exposed to the interstellar medium," said Opher.
Researchers are suggesting that exposure to interstellar clouds may have triggered multiple ice ages on Earth, changed the chemistry of the atmosphere on the planet and eventually led to the emergence of humankind.
Astrophysicists from Harvard University, Johns Hopkins and Boston University suggested that nearly two million years ago, the solar system clashed with a large and dense interstellar cloud because of which Earth was exposed to radiation which altered the planet's climate.
In a statement, astronomy professor at Boston University and fellow at Harvard Radcliffe Institute Merav Opher said, "This paper is the first to quantitatively show there was an encounter between the sun and something outside of the Solar System that would have affected Earth's climate."
“Stars move, and now this paper is showing not only that they move, but they encounter drastic changes," he added.
Meanwhile, in an email to Gizmodo, lead author of the study Opher said that the team is “still trying to quantify it with modern climate models” but due to an increase of hydrogen and dust “Earth would have entered an Ice Age.”
Earth pushed outside heliosphere due to interstellar cloud
A bubble, known as heliosphere, covers the entire solar system and protects planets from radiation as well as other damaging cosmic rays which can affect our DNA.
The shield is filled with charged particles which are emitted from the sun and are known as the solar wind.
The scientists suggested that an interstellar cloud is likely to have shrunk the heliosphere so much that Earth was left outside of it and it was exposed to the radiation of the galaxy as well as particles which may have cooled the climate.
When Earth was without the protection of the heliosphere, it was then exposed to the interstellar medium. This means the atmosphere of our planet was likely affected by the combination of gas, dust as well as the atomic elements left behind by exploding stars, which included iron and plutonium.
Watch: UK: Scientists concerned about the state of water “Only rarely does our cosmic neighbourhood beyond the solar system affect life on Earth,” said paper coauthor and the director of Harvard University’s Institute for Theory and Computation, Avi Loeb. “It is exciting to discover that our passage through dense clouds a few million years ago could have exposed the Earth to a much larger flux of cosmic rays and hydrogen atoms. Our results open a new window into the relationship between the evolution of life on Earth and our cosmic neighbourhood.”
According to the researchers, Earth was outside the heliosphere nearly 10,000 years.
"This cloud was indeed in our past, and if we crossed something that massive, we were exposed to the interstellar medium," said Opher.
(With inputs from agencies)
